Method of manufacturing a tub



W 193. c. J. RODMAN METHOD OF MANUFACTURING A TUB Filed July 14, 1936 2Sheets-Sheet l April 12, 1938. c RODMAN 2,114,150

METHOD OF MANUFACTURING A TUB Filed July 14, 1936 2 Sheets-Sheet 2Patented Apr. 12, 1938 UNITED STATES METHOD OF MANUFACTURING A TUBClarence J. Rodman, Alliance, Ohio, assignor to The Steel SanitaryCompany, Alliance,- Ohio,

corporation of Ohio Application July 14, 1936, Serial No. 90.527

1 Claim.

This invention relates to a method of manufacturing tubs, and isconcerned particularly with bath tubs, although the principles of theinvention may be utilized in manufacture of other articles of likecharacter. While the invention will be described in detail withreference to bath tubs, it will be understood that the word tu refers toany article of the general character of a bath tub.

Tubs have usually been made heretofore of cast iron with the aid of sandmolds. It has also been proposed to make tubs of sheet metal by joiningshaped sections in a variety of ways. A serious objection exists,however, to the manufacture of tubs by either of these methods. The

plumbing trade demands tubs of a relatively wide range of lengths. Thestandard sizes are 4 /2,

5" and 6', although special intermediate sizes are sometimes required.While the problem of satisfying this demand is not serious in the castiron field, it is vital in the sectional, pressed steel field. Theadditional patterns necessary for molding cast-iron tubs involveconsiderable expense, but it is relatively small compared to the cost ofthe dies heretofore necessary for shaping sheet steel sections toprovide' the several tub sizes required by the trade. The object of thisinvention, therefore, is to provide a sectional sheet steel tub and amethod whereby it can be manufactured in a variety of sizes, without thenecessity of duplicating the die equipment for each different size.

In accordance with the invention, I form a bath tub of the usual generaloutline from two stampings drawn from sheet steel. One stamping isshaped to form the portionv of the tube adjacent the drain opening,which I term the drainend blank. After trimming, this stamping or blankis relatively smart, representing only about 40 one-sixth of the entirelength'of the tub. The

drain-end blank is substantially identical for all sizes of tubs.

The other stamping forming part of each tub is shaped in the dies and,after trimming, is

45 butt-welded to the drain end by a flash welding process. The weldedseam is then ground smooth and the entire tub enameled. In order to provvide tubs of different overall lengths, I vary the length of the secondstamping which I term the 5 bell-end blank. To facilitate drainage, thebottoms of the bell ends, of all tubs are given a certain slope.According to my invention, I vary the degree of slope between differenttub sizes, so that the depth of the bell-end blank, at the 55 open endthereof adapted to-abut the open end of the drain-end blank, will be thesame for all sizes, so as to match up with identical drain-end blanks.

A complete understanding of the invention so may be obtained from thefollowing detailed description thereof, referring to the accompanyingdrawings illustrating a preferred embodiment and practice. In thedrawings,

Flgs. 1 to 3 are side elevations of tubs of different sizes made inaccordance with the invention;

Fig. 4 is a sectional view through the die for forming the drain ends ofthe tubs;

Fig. 5 is a sectional view of a finished drain-end blank;

Fig. 6 is a view similar to Fig. 4 showing the dies for shaping thebell-end blanks; and

Figs. '7 and 8 are views similar to Fig. 6 showing the shaping ofdifferent sizes of bell-end blanks.

Referring now in detail to the drawings, Figs. 1 to 3 show sheet metalsectional tubs of various sizes, which will be designated A, B and Crespectively. Each tub comprises a drain end l0 which is identical forall tub sizes, and a bell end. The bell ends for the several sizes areshown at Ha. lib and lie. The drain and bell ends are shaped fromsheetsteel by drawing in suitable dies, as

will be described in detail shortly. After draw-' ing, the resultingblanks, each having a bottom,

sides, one closedend and one open end, aretrimmed to a predeterminedlength and are then ready to have their open ends abutted, as shown inFigs. 1 through 3, and welded together, the position of the welded seambeing indicated at I2. The welded seam is ground down and the tub isthen ready for enameling, although any additional parts such assupporting feet, aprons, or the like, may be attached in any desiredmanner.

The dies for shaping the blanks forming the drain and bellends of thetubs are described in detail and claimed in application Serial No.48,664, filed November '7, 1935, by Harold W. Clark. for Method andapparatus for making metallic receptacles. The dies for making thedrain-end blanks are shown somewhat diagrammatically in Fig. 4 andconsist briefly of a die ring l5 supported on a suitable base it, ablankholder ring I! actuated by one of the slides of a toggle press, andcooperating with the die ring to retard flow of the edges of a sheet offlat stock during the drawing operation. To this end, the die ring andblank-holder ring are provided with a cooperating bead l8 and groove i9extending around the edges thereof. A punch 20 mounted on the otherslide of the press carries an extension 2| and cooperates with apressure pad 22 yieldably supported beneath it, on pistons reciprocablein pneumatic cylinders 22a, for example. The pad 22 has a filler block23 attached thereto.

The procedure in forming a stamping or blank for the drain end involvessimply the placing of a sheet of stock on the die ring l5 after thepunch 20 and the blank-holder ring I! have been raised. Elevation ofthepunch permits the pad 22 to rise to its normal position adjacent thedie ring l5.

The press is then operated to lower the blankholder ring I! and thepunch 28 successively. After the blank-holder ring has gripped the edgesof the stock, the punch extension 2| engages the middle portion thereofand, as it descends, forms it into the shape shown in Fig. 4. The inneredge of the stock is bent up as at 24 between the filler block 23 andthe extension 2|. This interposes resistance to flow of the metalbetween the extension 2l and the pressure pad 22. The bead I8 and groovel9 in the die ring and blank-holder ring similarly restrain flow of theedges of the stock. Some fiow actually takes place but it is relativelysmall in amount. After drawing, the drain-end blank is trimmed asindicated in Fig. 5. When so trimmed, it has a depth D.

The bell-end blanks are similarly drawn by the aid of a die ring 25, ablank-holder ring 26 and a punch 21, as shown in Fig. 6. The punch 21,however, has a removable bottom plate 28 which cooperates with apressure pad 29 having a shaped recess therein. The plate 28 and the pad29, as well as the die ring and blank-holder ring 25 and 26, areprovided with cooperating beads and grooves 38 and 3| to restrain flowof the material adjacent the edges of the stock.

After forming a bell-end blank, it is trimmed and is then ready forabutment with a drainend blank and welding thereto. The depth of theopen end of the bell-end blank, of course, must be the same as the depthD of the drainend blank, in order that the abutting edges registeraccurately for welding. The bottom of the bell-end blank is given aslope indicated by the angle c in Fig. 6, the plate 28 and the pad 29being shaped accordingly. This slope is chosen I with regard to thelength of the finished bell- .end blank so as to ensure proper drainagethereof.

In order to make other sizes of tubs, for ex ample smallersizes as shownin Fig. 8, it is only necessary to substitute for the plate 28 and thepad 29, a plate 32 and a pad 33 as shown in Fig. '7, or a plate 34 and apad 35 as shown in Fig. 8. The plate 32 and the pad 33 are shaped toprovide a bell-end blank having a bottom which slopes at an angle b asshown in Fig. 7, while the plate 34 and the pad 35 are shaped to providea blank having a bottom-slope angle a as shown in Fig. 8. The angles aand b are chosen with respect to the lengths of the bell-end blanks tobe made, so that when trimmed to length, these blanks will have at theiropen ends, a depth D whereby they are adapted for abutment and weldingto identical drain-end blanks as shown in Fig. 5, to provide tubs havingdifferent overall lengths as indicated in Figs. 1 to 3. Since the anglefor the longest tub is chosen to ensure proper drainage, this resultwill also be achieved in the shorter lengths since the angles a and bare greater than the angle 0.

It will be apparent frorn the foregoing that the invention makes itpossible to provide a series of tubs of various lengths utilizing adrain-end blank which is substantially identical for all tub sizes, andbell-end blanks which differ inlength and slope of the bottom, dependingon the overall length of the finished tub. The invention thus permits alarge economy in the manufacture of tubs in that the same die equipmentis used to form the drain ends of all sizes, and the same equipment,except for the removable bottom plates and pressure pads, is employed tomake the bell-end blanks for all sizes. The cost of extra sets ofremovable plates and pressure pads for difierent sizes of bell-endblanks is relatively small. It will be understood, furthermore, that thesize of the sheet of stock used for the bell-end blanks varies with theoverall length of the finished blank.

The advantages of tubs of sheet steel are so well recognized as torequire no discussion here. It is sufiicient to state that thisinvention, for the first time, permits a reduction in the cost of diesfor making sheet steel sectional tubs such that it is practical, from acommercial standpoint, to manufacture them. While I have illustratedtheinvention as applied to the manufacture of tubs and, specifically,two-piece tubs, it will be understood that it is also applicable to themanufacture of other analogous articles and is not limited to thosecomposed of only two stampings.

Although I have described the invention as applied to only threedifferent tub sizes, it may be extended to provide as many diiferentsizes as desired. An important feature of the invention, furthermore, isthat it permits the manufacture of odd or intermediate sizes, withouteven requiring special removable bottom plates and pressure pads. Sincethe angles of slope of the tub bottoms, a, b and c, are all quite small,it will be apparent that a slight change in the length of the bell-endblank will not involve a very great departure from the predetermineddepth D at the open end thereof. Manufacturing tolerances permit aslight variation in this figure so that, within limits, the bell-endblank may be trimmed longer or shorter than the standard length, inorder to provide odd or intermediate tub sizes, and still be capable ofsatisfactory welding to a drainend blank having a depth of D at the openend thereof.

While I have illustrated and described herein but a preferred embodimentand practice of the invention, it will be apparent that changes ineither or both may be made without departing from the spirit of theinvention or the scope of the appended claim.

-I claim:

In a method of making a tub of predetermined length, the stepscomprising providing a drain end blank for said tub, said blank having abottom, sides and one closed end, the other end being open, providing aplurality of bell-end blanks of different lengths to match saiddrain-end blank, each of said bell-end blanks having a-sloping bottom,sides and one closed end, the other end being open, the depth of all thebell-end blanks at the open end thereof being the same as the depth ofthe drain-end blank at its open end, and the slope of the bottoms of thebell-end blanks varying from one size to the next whereby to obtainaccurate registry of the meeting edges of the bell-end and drain-endblanks when their open ends are abutted, selecting one of said bellendblanks having a length such as to produce a tub of said predeterminedlength when welded

